Method of and apparatus for utilizing waste gases and heat from electric furnaces.



No. 630,283. Patented Aug. I, I899.

W. BDRCHERS.

IETIIOD OF AND APPARATUS FOR UTILIZING WASTE GASES AND HEAT FROI ELECTRIC FURNACES.

(Application. filed In; 6, 1899.) (lo Iodol.) 2 Sheets-Shae! I.

No. 630,283. Patented Aug. I, I899. W. BORCHERS. METHOD OF AND APPARATUS FOR UTILIZING WASTE GASES AND HEAT FROM ELECTRIC FURNACES.

, (A lien-i0 filad In 6 1899.) (I0 IOIIOL) pp n r 2 Sheets-Shoot 2,

u: NORRIS PETERS ca. wo'raumon WASHINGTON, u c:

UNITED STATES PATENT OFFICE.

wrLuE'LM BORCHERS, or AIX-LA-CHAPELLE, GERMANY.

METHOD OF AND APPARATUS FOR UTILIZING WASTE GASES AND HEAT FROM ELECTRIC FURNACES;

SPECIFICATION forming part of Letters Patent No. 630,283, dated August 1, 1899. Application filed March 6, 1899. Serial No. 708,018, (No model.)

} from Electric Furnaces; and I do hereby declare the nature of this invention and in what.

manner the same is to be performed to be particularly described and ascertained in and by the following statement, reference being had to the accompanying drawings and to the letters marked thereon.

In the working of electric furnaces, more especially those employed for the manufacture of carbid, attempts are sometimes made to discharge the product from the furnaceiu a liquid state, for which purpose some furnaces are heated externally in addition to in ternal electric heating. Other furnaces have been so constructed (and this again applies to the manufacture of carbidlthat a given quantity of the carbid is allowed to accumulate in a solidified form within the fusingchamber in order that the finished block may be subsequently withdrawn from the furnace or allowed to fall therefrom. The importance of carrying out the reaction in electric furnaces by excluding the air and utilizing the evolved waste gases for heating purposes has also been recognized. All furnaces and workingmethods, however,heretofore known present the following disadvantages: The carbid discharge from the furnace in a heated condition is liable to become partially burned. Portions of thecharge fall out of the furnace, together with the discharged carbid blocks, which are of comparatively large bulk,and the carbon in such portions of the charge is consumed, so that when reutilizing such charge fresh carbon must be added thereto, whereby more impurities than necessary find their way from the carbon ashes into the carbid. The gases on leaving the furnace carry off with them a considerable amount of floating dust containing carbon particles, which, being combustible, add the danger of fire to the inconvenience resulting from the float-- ing dust as such. The amount of power consumed in the manufacture of carbid is unduly high notwithstanding previous attempts to form of my improved resistance-heating fur- I nace. Fig. 2 is a transverse vertical section of the same, taken on the line 00 0c of Fig. 1. Fig. 3 is a horizontal section taken on the line y y of Fig. 1. Fig. 4 represents one form of furnace for are-heating. sectional views hereinafter referred to.

The smelting or fusing chamber Sthat is to say, the electric furnace proper, which is formed with thin walls and is provided with a water-jacket Dis arranged inside such jacket after the manner of a furnace in a steam-generator. y In the resistauceheating furnace represented in Fig. 1 the electrodes E are inserted in a suitable manner from opposite sides into the furnace.

In the arc-heating furnace represented in vertical section in Fig. 4 one electrode isinserted vertically through the hopper and the other vertically from below through a hinged bottom or hearth H, capable of turning up or down and when opened allowing the cooled carbid block to be removed from the furnace. This hinged bottom is secured in its closed position by a lever M, provided with a counterweight. I

The electrodes E for enabling the current to traverse the charge consist of carbon rods or plates, between which either the heating resistance W, consisting of a solid carbon body or a core of rammed pulverized carbon, is inserted or the said rods or plates may be so arranged that between them a voltaio are can be struck. (See Figs. 4, 5, and 6.) The said electrodes are properlyinsulated at the places where they traverse the furnace-walls.

The charge as far as his not rammed into the furnace and as far as supplementary feeding is necessary is fed from a feed-hopper T, filled with pulverized material to such an extent as to prevent escape of gas.

Figs. 5 and G are In the interior of the furnace is an inclined perforated metal plate or diaphragm 1'3, arranged at the natural angle of repose of the surface of the charge. The space above this diaphragm is filled with wood debris or shavings, coarsely-granulated charcoal, or other vegetable or animal fibrous or porous material F, of a similar nature, capable of retaining dust particles. This d u st-retaining filter is, in order to prevent its destruction, arranged, as shown, upon those parts of the charge which remain comparatively cool.

From what is generally known about electric furnaces and the method of charging and discharging furnaces of the construction in question no further explanation is necessary.

When the furnace is at work, the gases escaping from the charge (which by preference should not be too finely granulated) pass through the above-mentioned filter in the upper part of the furnace, where the floating dust is retained. Thence the said gases, practically free from dust, pass through a suitably-arranged gas-discharge pipe B into a collecting-receptacle or directly into a feed-pipe, from which they may be taken away for working gas-engines. The size of the furnace and the quantity of the charge are so adjusted that after the carbid block has been entirely fused it will still be inclosed on all sides in sufficiently thicklayers of undecomposed charge. Owing to the latter being in contact with the walls (kept cooled by the surrounding water) the said charge remains electrically non-conductive during the whole period-of work, so that notwithstanding the metal walls of the furnace the insulation of the electrodes and of the smelting products causes no difficulty. After the working is completed the finished carbid block is left for several hours in the furnace, as owing to the high temperature a considerable amount of heat still remains accumulated therein, which as it gradually passes off may be utilized for the generation of steam. \Vith properly-constructed furnaces the generation of steam commences when one such furnace has been at work for two hours. If, therefore, a series of furnaces of this kind be arranged in one comparatively large steam-boiler, in which one furnace is worked after another successively, and if the carbid blocks be allowed to cool down therein, the generation of steam will go on continuously and may be utilized for the generation of power. A diagrammatic arrangement of this kind is represented in longitudinal section in Fig. 5 and in transverse section in Fig. 6.

The method of cooling the carbid block in the closed furnace apart from the possibility of utilizing the excess of heat olfers the further advantage that any undecomposed charge which naturally falls out of the furnace or is withdrawn therefrom, together with the finished carbid block, is so cold that the carbon contained therein is no longer consumed, as was heretofore believed to be unavoidable.

Experiments have proved that by utilizing the waste gases and the excess heat existing in the finished carbid theoretically more than a third-in practice more than a fourth-of the power heretofore used for the manufacture of carbid is saved and that none of the charge becomes covered with or choked by dust; also, that the excess of charging material employed for protecting the f urnace-wall admits of being used again at any time without furthercarhon being added thereto.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. The method of utilizing the waste gases and heat from electric furnaces, consisting in effecting the electric smelting or reduction in the interior of a steam-generator in the presence of an excess of the charge which remains undecomposed, filtering the gases generated in the furnace to free the same from dust particles, and cooling the molten product in the furnace, as set forth.

2. In an electrical furnace,a smelting-chamber provided with an inclined perforated diaphragm at the upper end thereof, and a filtering material located above and supported upon said diaphragm, in that portion of the device which remains comparatively cool, as and for the purpose specified.

3. In a device of the character described, a furnace, a hopper for feeding material thereinto, electrodes extending into said furnace, an inclined perforated diaphragm located in the upper portion of the furnace extending from the bottom of the hopper, and a filtering material of vegetable or animal fibers supported upon said diaphragm, as set forth.

4. The combination with a steam-generator, of a series of electric fu rnaees arranged therein and each having a filtering device near its upper portion, electrodes in each furnace and connections substantially as described whereby said furnaces may be worked successively, as set forth.

In witness whereof I have hereunto set my hand in presence of two witnesses.

WILI-IELM BOROHERS.

Witnesses:

C. E. BRUNDAGE, G. Scorr.

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